The present invention relates to a computer system for preventing duplication or copying of a program.
A program (either an operating system program or a utility program) to be executed by an office computer or a personal computer is generally stored in a storage medium such as a floppy disc or a cassette tape. If such a program stored in a storage medium is copied, this program can be executed with another machine of the same type. However, if a program can be copied easily, this infringes upon the rights of a person who develops and sells a general-purpose program. Therefore a demand exists for a copy-prevention method.
In view of this, a method has been proposed for modifying a program according to a machine number unique to each machine, so that a particular machine alone can execute the program. However, this method is disadvantageous in that a program supplier must modify each software medium accompanying each machine. Furthermore, when a software item is general purpose, the type of machine used to execute the software item is not specified. For these reasons, the above method is impractical.